In the hunt to replace petroleum, scientists are looking for more efficient ways to produce biofuels from organisms. A team of researchers at MIT have engineered yeast to manufacture the heavy alcohol isobutanol. Yeast normally creates isobutanol in small amounts, and by altering the cell so that the production takes place entirely in the mitochondria, the scientists were able to boost the amount of the chemical by 260 percent. The results of their work were published in the February 17 online edition of Nature Biotechnology.

Led by chemical engineering professor Gregory Stephanopoulos, a group of MIT scientists has made strides in altering the cell structure of yeast to produce more isobutanol. In the past, researchers have tried to reduce the amount of the chemical, as it can ruin the flavor of wine and beer. Now, “there’s been a push to try to make it for fuel and other chemical purposes,” says Jose Avalos, the paper’s lead author.

Yeast usually makes isobutanol in two separate locations through a series of steps inside the cell, either in the mitochondria or the cytoplasm. By engineering the metabolic pathway’s enzymes to direct the cell to shift the production exclusively inside the mitochondria, they were able to boost the amount of isobutanol by 260 percent as well as raise the levels of isopentanol by 370 percent and 2-methyl-1-butanol by 500 percent.

“Enzymes from the second phase, which are naturally out here in the cytoplasm, have to wait to see what comes out of the mitochondria and try to transform that. But when you bring them into the mitochondria, they’re better at competing with the pathways in there,” Avalos says.

While still not able to generate enough isobutanol on an industrial scale, the technology holds the potential to open up biosynthetic pathways for a whole host of other chemicals. Currently, the researchers are still working towards increasing the production of isobutanol while reducing the amount of ethanol, a major byproduct of sugar breakdown.